Intact platelets and platelet extracts have been studied by biochemical analysis and by the nuclear-magnetic-resonance examination of fluorinated psychoactive drugs and amines, and phosphorylated compounds of low molecular weight. Lithium contained in model systems, platelets, and red blood cells has also been studied by nuclear-magnetic-resonance. Some chemical and physical concomitants of drug, amine, and nucleotide storage have been determined, and correlated with differences in the composition of storage vesicles. The lithium resonance in model systems and cells appears to reflect the water content and relative motional restriction of the immediate environment.